Time switch for electrical circuits



April 22 1924. 7 1,491,591

, E. L. EDWARDS TIME SWITCH FOR ELECTRICAL CIRCUITS Filed July'ls, 1920 2 Sheets-She et 1 WITNESS: IN VEN TOR:

a w @h LM/M ATTORNEY.

2 S heet's:%;leet 2 April 22 1924. I E. L. EDWARDS TIME SWITCH FOR ELECTRICAL CIRCUITS Filed July 15 1920 uuuul'uulu 5 7d 217 4d w a w 2 IN VEN TOR:

I A TTORNEY.

WITNESS.- CL M.

' Patented Apr. 22, 1924.

UNITED STATES 1,491,591- PATENT OFFICE.

EDWIN LwEOWARDS, Of INDIANAPOLIS, INDIANA, ASSIGNOB TO EDWARDS X-RAY CORPORATION, OF INDIANAPOLIS, INDIANA, A COBPOBATIONOF INDIANA.

TIME SWITCH FOB ELECTRICAL CIRCUITS.

Application filed July 15, 1920. Serial No. 396,560.

T all whom it may concern Be it known that I, EDWIN L. EDWARDS, a citizen of the United States, residing at Indianapolis, in the county of Marion and State 6 of Indiana, have invented a new and useful Time Switch for Electrical Circuits, of which the following is a specification, reference being had to the accompanying drawings and to the letters and figures of reference 10 marked thereon.

This invention relates to means for automatically breaking an electrical current after the circuit has been established, the invention having reference more particularly )5 tee time switch that is designed to be used in connection with an X-ray apparatus, for

automatically breaking the-electrical circuit required for operation ofthe X-ray tube.

An object of the invention is tov provide an efiicient and reliable time switch'which shall be adapted to operate to eliminate trouble of possibly serious nature which might result from continuance of the use of elec his current beyond a definite period oftime.

Another ob ect is to enable 0 erators of X-ray apparatus to avoid vserious conseuences due to over-exposureto the X-ray;

t e purpose more specifically being to pro: vide apparatus to control an electrical cirsuit sothat the circuit shall be instantly broken aftera definite period of time, with- V out depending upon the operator to break the circuit when he may be engaged in making observations or directing operations and I an unintentionally prove to be unreliable as a timer. w a

-A still further object is to provide improved apparatus whereby the eriod of 'action of an'electrical force may e accurately 4c timed or measured, 'and the current automati'cally switched off at the end of the period of time desired, more particularly to time the use of high-tension current when failure of the operator to turnoff the current at the proper time might result in serious consequences.

lV'th the above-mentioned and other objects in. view, the invention consists in an electrical control system involving high- .30 tension current, the switching on of. the current, and the timing and automatic switching oil of the current after having been used during a definite period of time; and, the invention consists also further in an im- 66 proved timing device and in the features or ranged; Fig. '2 is an elevation ofthe time switch on an enlarged scale as preferably constructed, portions being broken away,

and a diagram of the electrical system involved; Fig. 3 is a fragmentary transverse section showing details of portions of the preceding figure; and Fig. 4 is a plan of a timing indicator of preferable form.

Similar reference characters in the various figures of the drawings indicate corre-' sponding elements or features of construction herein referred to in detail.

For the purpose of clearly explaining the invention and its importance in one of the useful and advanta of, so much of an -ray apparatus as may be associated with the invention is shown in the drawings and comprises a cabinet which ous applications therehas a bottom 1, a side wall 2 provided withp a door 3, and a top 4; and by broken lines is illustrated a crane-like holder comprising a column 5, on the top of the cabinet and having an arm 6, provided with suitable hangers 7, supporting an X-ray tube 8, the arm having posts 9, l0 and 11 thereon to support a circuit wire. A transformer 12 is arranged on the bottom of the cabinet, and a high tension circuit 13 leads from the transformer over the' posts to the X-raytube, usually through a. protecting guide tube 14 the transformer commonly having binding posts 15 and 16 for readily connecting circuit wires with the transformer.

The time switch, or electrical circuit breaker, preferably is' mounted as a unit on v a suitable base 17, which may be wooden or composed of non-conducting materialand arranged on the side wall 2 of the cabinet. A base plate 18 is fixedly mounted on the base17. and supports aswitch bar 19, having a suitable contact point 20. Another base plate 21, is mounted also on the base 17 and supports an elastic switch arm 22 which extends under and beyond the bar 19 and has a contact point 23 opposite to the point 20 and held in contact therewith when the switch arm is not forced from the switch bar to a stop bracket 24, mounted on the base 17 and in some cases having an insulator 25 upon which the switch arm may rest. A solenoid 26 is suitably arranged on the base 17 above the stop bracket 24 and its armature 27 preferably is cylindrical, and being vertically arranged its lower end may hold the switch arm 22 to the stop bracket 24, the armature preferably having an insulating lower end 28. The armature has a projection 29 on its upper portion that extends upward beyond the main portion of the solenoid. A bracket 30 is secured to the base 17 and beneath the bracket a switch base 31 is suitably supported and may be a non-conducter or provi ed, as may be required, with insulation. The switch base supports a switch bar 32 preferably having a suitable contact point 33. A switch plate 34 is secured to the switch base and supports an elastic switch arm 35 opposite to the bar 32 and having a contact point 36 which is held by the switch arm in contact with the point 33, being designed for breaking or opening the circuit at the end of a. definite period. A circuit wire 37 is connected with one end of the primary coil 38 of the transformer and with the base plate 21. A circuit wire 39 is connected with the base plate 18 and also with the switch plate 34. A circuit wire 40 is connected with the switch bar 32 and also with a suitable battery or source of electrical energy 41 with which a circuit wire 42 is also connected by means of a branch 43,"the wire 42 being connected with the opposite end of the primary coil 38 and also with one end of the winding of the solenoid 26. The wires 40 and 43 in ractice may be arranged in a cable or casing 44 extending outside of the cabinet and provided with a suitable con nector 45 whereby to connect the circuit wires with a current supply circuit. A circuit wire 46 is connected with the opposite end of the solenoid winding and also with a suitable switch 47, another circuit wire 48 being connected with the switch and also with the circuit wire 39. In the drawings the switch is symbolically illustrated, but in practice as seen in Fig. 1 the switch wires 46 and 48 are arranged in a cable or casing 49, extending through the cabinet wall and having the switch connected therewith outside the cabinet.

The timing device preferably comprises a hollow cylinder 50 which is vertically arranged and has a bottom 51, and at a suit able distance from the top of the cylinder its wall has a small aperture 52 to permit the cylinder to be supplied with a suitable liquid or to permit the liquid to be readily replenished as required. The cylinder is se-.

cured to the base 17 by suitable clamps 53 and 54 permitting vertical adjustment of the cylinder if desired. The top portion of the cylinder has a head 55 thereon, in which is a central aperture 56. A heavy piston 57 is arranged in the cylinder to freely slide while being closely fitted so as not to require packing, the piston being designed to descend by the force of gravity. The cylinder is usually supplied with water which tends to cause uniform speed of the descending piston, which has a vertical channel 58 and in some cases a second channel 59 to permit the water to pass through the piston. Preferably a screw plug 60 is inserted in the wall of the piston and extending to one of the channels and having a conical valve point 61 which is designed for choking the channel more or less as may be desired. A flexible cable or cord 62 is connected to the piston and extends through the head 55 for lifting the piston and assisting in controlling the descent of the piston.

As a preferred means for control of the piston, the bracket 30 has standards 63 and.

'64 thereon, in which a shaft 65 is rotatively mounted, and extending through the base 17 and the side wall 2 of the cabinet. A grooved wheel 66 is secured to the shaft and has two stop blocks 67 and 68 on one side thereof to be moved into contact with o posite sides respectively of the standards, these stop blocks preferably having adjusting screws 69 and 69' that may be projected from the stop blocks to vary the extent of movement of the wheel. The cable 62 is secured in one of the grooves of the wheel to enable the wheel to partially wind'up the cable or to unwind it. A journal box 70 is arranged in the wall 2 of the cabinet and assists in supporting the shaft 65 which is designed for winding up the cable 62 and to operate as an indicator spindle. The journal box has an indicator dial 71 fixed thereon, which is located on the outer side of the cabinet wall, and the shaft has a ,knob 72 fixed thereon, a pointer 73 being fixed to the knob to sweep the dial which has an indicator scale 74 thereon with which the inter is designed to co-o rate. The scale is suitably graduated an the graduations suitably numbered, as 1 to 15 inclusive, to indicate seconds of time, for instance.

A suitable lock is provided essentially for temporarily preventing the operation of the timing device until the moment when the measurement of the time should begin, and in the referred construction one of the standards is provided with a pivot 75 to which a lever 76 is connected, being below the wheel 66, and the lever extends above the extension 29 of the solenoid armature to be lifted thereby, a brake band 77 being arranged in a groove of the wheel and connected to the lever, the arrangement being such as to enable the lever by reason of its weight and the force of gravity to tighten the band on the wheel and lock the wheel against movement by the weight of the pis' ton 57, but permitting the wheel to be forcibly rotated by means of the knob72 to raise the piston.

For the purpose of assistingeto regulate the speed of the piston 57 when descending so that the extent of movement of the wheel 66 shall be in accordance with the graduated dial or scale, a friction-brake preferably is provided and comprises a base member 78 secured to the bracket 30 and having an elastic arm 7.9 thereon, which has a contact shoe portion 80 arranged in contact with the periphery of thewheel 66. The tension of the arm 79 maybe delicately adjusted by means of an adjusting screw 81 arranged in the bracket 30 and extending against the under side of the arm. In case the displacement of the liquid from beneath the piston through the piston does not insure the correct speed of the piston while descending, the tension of the brake may be adjusted to compensate for previous miscalculation in making adjustments orto compensate for differences in the character of liquid which may be used in the timing cylinder.

By reference to Fig. 2 it will be seen that the devices 19 and 22 which constitute an automatic circuit connector are normally apart so that the circuit is open when the manually operated starting switch 47 is open while the switch elements 32 and 35 constituting the circuit breaker are together so as to close the circuit which is to beamtomatically opened at the required time instead of depending upon.the operator to open the switch 47 or permit the switch to open precisely at the proper time. 4

When the X-ray machines are produced in a factory "they may be provided with such time switches as may be desired and of more or less costly design to suit the customer. It is preferable to ship the machine with the .timer cylinder empty, to be supplied with a suitable liquid when the machine is set up for use at which time adjustments may be made as required. It should be understood adjustments may be made if desired to permit fairly accurate timing without the use of a liquid in the timing cylinder, in which case descent ofthev piston would be governed by air pressure beneath the piston, the channel in the piston permitting escape of air at uniform velocity. The indicator scale being fixed in the factory, usually to indicate a maximum period'of 15 seconds of time, it should be understood that adjustments may be readily made by theoperator to insure the breaking of the circuit at the end of a definite period, using the indicator as a basis for calculations.

In practical use, the circuit wires being in connection with a source of electricity,

and it being desired to use the electrical used, the timer piston is manually caused to be'drawn up in the cylinder until the starting point is indicated on the timing scale, the piston then being temporarily held by the lock or brake which is provided for the purpose. lVhen the operator is ready to begin using the electrical current he manipulates the hand switch 47 to close the circuit, resulting in the solenoid being energized so that its armature causes the release of the lock orbrake and at the same time causes or permits the establishment of the electrical circuit, which may be through the transformer, while the timing piston is permitted to descend in the timing cylinder at uniform speed. The starting point may be at any graduation mark desired on the indicator scale. In the operation of the structure the piston descends until the stop block 67 is carried around to the breaker switch arm 35 which is opposite to the standard 63, the arm being then engaged by the stop block and forced over to the standard with the result that the contact point 36 is separated from the contact point 33 and the circuit broken or opened. When the electrical circuit is broken or opened the solenoid becomes de-energized so that its armature is permitted to descend and cause.

the further breaking of the electrical circuit, by retracting the switch arm 22. The electrical circuit having been positively and accurately broken or opened at the end of the desired period of time, the operator may leisurely cause or permit the hand switch 47 to be opened, after which the apparatus remains dormantor inoperative until again required for use.

Having thus described the invention, what" is claimed as new is-- 1. An electrical circuit time switch including an upright hollow cylinder, a weighted piston movable in the cylinder, a rotary wheel and a cable to lift or to permit descent of the piston and provided with locking means therefor including a ivoted automatically-operating actuating ever, a brake operating on the wheel, a solenoid supported in proximity to and controllin the lever, and a circuit breaker control ed by the wheel.

2. An electrical circuit time switch includin an upright hollow cylinder, a piston movabIe in the cylinder and having a channel extending therethrough, controlling means to lift or to permit descen of the J control the wheel, and means controlled by the wheel to alternately break and make an electrical circuit with the breaker device.

3. An electrical circuit time switch including an upright hollow cylinder, a piston movable in the cylinder, a rotary wheel and a cable to lift or to permit descent of the piston, a supported solenoid having an armature with upper and lower extensions, locking means for the wheel including a pivoted automatically-operating actuating lever having an arm opposite to the upper armature extension to be controlled thereby, a brake operating on the wheel, a circuit connector controlled by the lower armature extension, and a circuit breaker controlled by the rotary wheel.

4. An electrical circuit time switch including an upright hollow cylinder, a piston movable in the cylinder and having a channel extending therethrough, controlling means to lift or to permit descent of the piston including a rotatable wheel and a cable extending about and secured to the wheel and having connection with the piston, a brake operating on the wheel, a sup ported solenoid having an armature with an extension, a circuit connector controlled by the armature extension, an electrical circuit breaker device, and means controlled by the wheel to alternatively break and make an electrical circuit with the breaker device.

5. An electrical circuit time switch including a vertical rotary wheel having a block on one vertical side thereof, a vertical hollow cylinder arranged lower than the wheel, a supported switch bar arranged in proximity to the wheel, a piston movable in the cylinder, a cable connected with the piston and extending over the periphery of the wheel and secured thereto, a brake operating on the wheel, a supported elastic switch arm having electrical connection with the switch bar and extending into the path of movement of the block on the wheel to be moved and held thereby from connection with the switch bar, and means to limit the rotary movement of the wheel.

6. An electrical circuit time switch including a hollow stationary vertical cylinder, a piston movable in the cylinder, a rotatably supported wheel having a horizontal axle fixed thereto, a cable connected to the piston and the periphery of the wheel enabling the wheel to lift the piston, means connected to said axle to rotate the wheel in one direction to lift the piston, friction-hold locking means operating on the wheel to prevent descent of the piston with rotation of the wheel in the opposite direction, an electrical circuit breaker device, and means controlled by the wheel to alternately break and make an electrical circuit with the breaker device, with means to graduatedly retard rotation of the wheel.

7. An electrical circuit time switch comprising a supported standard, a supported switch bar extending opposite to the standard, a supported elastic switch arm extending between the standard and the switch bar and beyond the end of the bar, the arm having electrical connection with the bar, a wheel rotatively mounted on the standard and having a block on one side thereof to engage the switch arm and push the arm to the standard, a hollow vertical cylinder, a piston movable in the cylinder, and a cable connected with the piston and extendin over the periphery of the wheel and secure thereto.

8. In an electrical circuit time switch, the combination of a vertically-supported hollow cylinder with a closure in the bottom thereof, a piston closely fittin in and movable in the cylinder and having a channel extending vertically therethrough, a valve adjustably secured in the piston and extending transversely into the channel, a wheel rotatively supported, a cable connected with the piston and the periphery of the wheel, two supported contacting circuit breaker elements, and a device operated by the wheel to engage one of said elements and move it from contact with the other.

9. In an electrical circuit time switch, the combination of a vertical hollow cylinder with a closed lower portion, a piston movable in close-fitting arrangement in the cylinder and having a channel extending vertically therethrough, a wheel rotatively supported, a cable connected with the piston and the periphery of the wheel, a lever pivotally supported, a brake band extending about the wheel and connected to the lever adjacent to its supporting pivot, two supported contacting circuit breaker elements arranged in proximity to the wheel, and a device operated by the Wheel to engage and move one of said elements from contact with theother.

10. In an electrical circuit time switch, the combination of a vertical hollow cylinder, a piston m'ovable in the cylinder, two supported contacting circuit breaker elements, a wheel rotatively supported and having a device operated thereby to engage and move one of said elements from contact with the other, a cable connected with the piston and the periphery of the wheel. a lever pivotally supported adjacent to the wheel, a brake band extending about the wheel and connected to the lever adjacent to its supporting pivot, a supported switch device, a supported elastic switch arm arranged below the switch device to contact therewith, and a controlling device movably guided to alternately control the lever and the switch arm. I

11. In an electrical circuit time switch, the combination of a vertical hollow cylinder,

a piston movable in the cylinder, ported contacting circuit breaker a supported indicator dial, a shaft rotativel supported and extending through the dial, a knob fixed to the shaft and having a pointer there-on opposite to the dial, a wheel secured to the shaft, a cable connected with the piston and the periphery of the wheel, a device carried by the wheel to engage one of the said elements and move it from two supelements,

contact with the other, able to the wheel, and operate on the wheel.

In testimon whereof, I afiix my signature in presence of two witnesses.

EDVIN L. EDVARDS.

a governor adjusta locking device to Witnesses:

E. T. SILVTUS, R. H. SAMPLE. 

